1. Field of the Invention
This invention relates in general to telecommunications systems. In particular, the invention relates to a packet switched telephony network that can interface with the long established circuit switched telephony network.
2. Background Art
In recent years, voice, video, and data communication networks have rapidly converged, resulting in vast increases in the power and flexibility of modern communications. In effectuating the next step of this convergence and development, it becomes highly desirable to transmit voice communications over the same types of efficient, packet-switched networks currently used for data transmission. By routing multiple types of communications over a common network, providers of multiple communications services can exploit the efficiencies of packet communications, and potentially avoid the added expense of developing and/or maintaining multiple networks.
However, while converting to a packet-switched network for voice communications would offer many advantages to communication service providers and consumers alike, there already exists a vast and complex pre-existing communications infrastructure based upon circuit-switched telephony protocols. Thousands of telephony features have been implemented within the legacy circuit-switched networks, which require great effort and time to be designed into a new packet network. Moreover, the existing circuit-switched and newer packet switched networks are not directly compatible due to substantial differences in the format and transmission protocols between circuit-switched networks and packet-switched networks. The sheer magnitude and complexity of circuit-switched telephony systems already in place make it unfeasible to both develop and install a packet-switched network that completely and immediately replaces the legacy of circuit-switched networks.
As a result, it is an object of this invention to provide a packet-switched network for the conduction of telephonic communications, which interfaces with the legacy circuit-switched network when necessary. While it is understood that the packet-based telephony system can readily interface with the circuit switched system in a variety of network positions using the techniques described herein, this invention specifically discloses an embodiment for routing call traffic between Local Exchange Carrier (“LEC”) access tandems over a packet-based network. It is also an object of this invention to allow the packet-switched network to seamlessly hand off calls to an existing circuit-switched network when the calls require telephony features that are not yet implemented in the packet-switched network.
While telecommunication service providers can stagger the introduction of advanced features into a packet-switched network by handing off calls invoking unsupported features to the legacy network, such an approach would be very costly and time consuming to implement if it required the addition or modification of signaling inputs to the many existing legacy switching systems in order to effectuate such inter-system routing. Therefore, a further object of this invention is to provide a packet-switched network which can interface with the circuit-switched network without requiring new signaling inputs, or any other changes to the legacy circuit-switched network infrastructure.
These and other objects of the present invention will become apparent to those of ordinary skill in the art in light of the present specifications, drawings and claims.